The hosts file may also be blocking the iTunes Store.
If you want to have Windows try to restore the hosts to default, follow the "FixIt" in How do I reset the hosts file back to the default?.
Note: Work systems may put information into the hosts file. Consult whomever is responsible for supporting Windows on your system before resetting the hosts file to default.
If restoring the defaults did not resolve the issue, you can find your hosts file at C:\WINDOWS\SYSTEM32\DRIVERS\ETC .
Select the hosts file. Choose Edit > Copy, and then choose Edit > Paste.
There should now be a duplicate of the hosts file named "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7).
Drag the original hosts file to your Desktop. If Windows needs your permission to continue, click Continue.
Drag the "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) to the Desktop.
Right-click "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) and choose Open. You may be prompted to choose the program you want to use to open this file. Double-click Notepad.
When Notepad opens, choose Edit > Select All, and then choose Edit > Delete.
From the File menu,choose Save. Quit Notepad.
Drag the "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) file from your Desktop back into the original location (given in step 2). If Windows needs your permission to continue, click Continue.
Right-click the "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) file, and choose Rename. Type "hosts" (without quotation marks) and press Enter.
Restart your computer and try connecting to the iTunes Store.